Do I need advanced SQL to attempt this?

This problem is labeled as Intermediate. You don’t need to be an expert, only comfortable with SQL and willing to experiment. If you get stuck, the hints and solution will help you along.

Will I get hints and step-by-step explanations if I get stuck?

Yes. Every problem comes with optional hints you can reveal one at a time, plus a fully worked step-by-step solution. Hints and solutions will link to Learning Pages where you can get more information about particular concepts. You decide how much help you want while practicing.

Practice SQL Window Functions | Xorthax's Trading Post

Tables Used

orderdetails

Column	Type
orderdetailid	bigint
orderid	bigint
productid	bigint
quantity	bigint
unitprice	double precision
currencyid	bigint

orders

Column	Type
orderid	bigint
customerid	bigint
orderdate	timestamp without time zone
totalamount	double precision
status	text

Expected Output

Column
productid
orderdate
quantity
previousquantity
quantitychange

6. How Much More Did They Order?

Track changes in quantity across each product's order timeline.

Xorthax wants to analyze purchasing patterns. For each Product ID, calculate the change in order quantity compared to the previous order (as determined by order date).

Write Your Query

This problem is labeled as Intermediate. You don’t need to be an expert—just comfortable with SQL and willing to experiment. If you get stuck, the hints and solution will guide you step by step.

Yes. Every problem comes with optional hints you can reveal one at a time, plus a fully worked step-by-step solution. You decide how much help you want while practicing.

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